diff options
Diffstat (limited to 'crypto/dh/dh_check.c')
| -rw-r--r-- | crypto/dh/dh_check.c | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/crypto/dh/dh_check.c b/crypto/dh/dh_check.c new file mode 100644 index 0000000000..8da8dc8393 --- /dev/null +++ b/crypto/dh/dh_check.c @@ -0,0 +1,120 @@ +/* crypto/dh/dh_check.c */ +/* Copyright (C) 1995-1997 Eric Young (eay@cryptsoft.com) + * All rights reserved. + * + * This package is an SSL implementation written + * by Eric Young (eay@cryptsoft.com). + * The implementation was written so as to conform with Netscapes SSL. + * + * This library is free for commercial and non-commercial use as long as + * the following conditions are aheared to. The following conditions + * apply to all code found in this distribution, be it the RC4, RSA, + * lhash, DES, etc., code; not just the SSL code. The SSL documentation + * included with this distribution is covered by the same copyright terms + * except that the holder is Tim Hudson (tjh@cryptsoft.com). + * + * Copyright remains Eric Young's, and as such any Copyright notices in + * the code are not to be removed. + * If this package is used in a product, Eric Young should be given attribution + * as the author of the parts of the library used. + * This can be in the form of a textual message at program startup or + * in documentation (online or textual) provided with the package. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * "This product includes cryptographic software written by + * Eric Young (eay@cryptsoft.com)" + * The word 'cryptographic' can be left out if the rouines from the library + * being used are not cryptographic related :-). + * 4. If you include any Windows specific code (or a derivative thereof) from + * the apps directory (application code) you must include an acknowledgement: + * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" + * + * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * The licence and distribution terms for any publically available version or + * derivative of this code cannot be changed. i.e. this code cannot simply be + * copied and put under another distribution licence + * [including the GNU Public Licence.] + */ + +#include <stdio.h> +#include "cryptlib.h" +#include "bn.h" +#include "dh.h" + +/* Check that p is a strong prime and + * if g is 2, 3 or 5, check that is is a suitable generator + * where + * for 2, p mod 24 == 11 + * for 3, p mod 12 == 5 + * for 5, p mod 10 == 3 or 7 + * should hold. + */ + +int DH_check(dh,ret) +DH *dh; +int *ret; + { + int ok=0; + BN_CTX *ctx=NULL; + BN_ULONG l; + BIGNUM *q=NULL; + + *ret=0; + ctx=BN_CTX_new(); + if (ctx == NULL) goto err; + q=BN_new(); + if (q == NULL) goto err; + + if (BN_is_word(dh->g,DH_GENERATOR_2)) + { + l=BN_mod_word(dh->p,24); + if (l != 11) *ret|=DH_NOT_SUITABLE_GENERATOR; + } +/* else if (BN_is_word(dh->g,DH_GENERATOR_3)) + { + l=BN_mod_word(dh->p,12); + if (l != 5) *ret|=DH_NOT_SUITABLE_GENERATOR; + }*/ + else if (BN_is_word(dh->g,DH_GENERATOR_5)) + { + l=BN_mod_word(dh->p,10); + if ((l != 3) && (l != 7)) + *ret|=DH_NOT_SUITABLE_GENERATOR; + } + else + *ret|=DH_UNABLE_TO_CHECK_GENERATOR; + + if (!BN_is_prime(dh->p,BN_prime_checks,NULL,ctx)) + *ret|=DH_CHECK_P_NOT_PRIME; + else + { + if (!BN_rshift1(q,dh->p)) goto err; + if (!BN_is_prime(q,BN_prime_checks,NULL,ctx)) + *ret|=DH_CHECK_P_NOT_STRONG_PRIME; + } + ok=1; +err: + if (ctx != NULL) BN_CTX_free(ctx); + if (q != NULL) BN_free(q); + return(ok); + } |